Amplifier connection



Jan. 15, 1929.

W. WOLFF AMPLIFIER CONNECTION Fil ed April 7, 1925 (l M c 0 6 5 7 6 PPb/bbb 1 /En Q 3 24F K4 2/ Inventor: Walther WOIFF, y His Attorney.

Patented Jan. 15, 1929.

UNITEDI STATES 1,699,129 PATENT one me.

WALTHEB woLrF; or BERLIN-KOPEMCK, GERMANY, ASSIGNOB ro GENERAL ELECTRIC ccmrnNY, A? conronnrron on NEW Yomr.

AIPLIFIEBICONNECTTONQ application filed April 7, 1925, Serial Ho. 21,429, and in Germany May 23, 1924.

My present invention relates to operatingconnections for fhBIIIllOIllC' amplifiers, andmore particularly to means for closingor opening a heating circuit for the cathodes ot' thermionic amplifiers from a distant point.

In some cases it is founddesirable, where thermionic amplifiers are employed inlongf distance telephone lines, to have means'provided whereby an operator who controls the transmission over the line may be-abl'e at will to close or open the heatingcircuit for the cathodes of amplifiers which are lcicated" at an intermediate point in the telephoneline.

The object ofmy invention is to provide a simple and reliable means wherebythis result may be accomplished. I

I have found thatthe object of my invention maybe readily attained by providing means for closing. the heating circuit which responsive to current of one particular character, and meansfor openingthe heating circuit which is responsive to current oi a different character.

The novel features which Ibelieve" to be' characteristic of my" inventionare set forth with particularity in the appended claims. My invention itselfihowever, both asto its organization and method of operation, will best be understood by reference tojt'he' fol lowing description taken in connection with the accompanyingdrawing in which 1 is connected at points 3, a to theamplifying system. The trunk line is coupled by means oi a transformer 5 to the amplifiers. Between the points 6, and 7, in the secondary circuit of transformer 5 the winding 8 of an alternating current relay is connected. The filaments 9 of the amplifier tubes are con nected to a local battery 10 through contacts 11 and 12 of the two relays having windings 18 and 14. For convenience in description and to simplify the drawing, the connections of the amplifier input and output whereby the voice currents received over the lines 1 and 2 are amplified, have been omitted.

be controlled from either direction.

Wl1en the operator at p, a distant point wishes to place the amplifier in operative condition for amplifyingspeech current, an alternating current impulse is transmitted over the line 1, 2. This operates relay Sand closes the contact at 15. This closes the circuit of a relay 16 through a battery 17. The relay 16, being energized, closes a contact at 18 and thus closes the heating circuit for the filaments 9; At the same time the relay 13 is energized and closes contact at 11, thereby holding the heating circuit closed after the contact at 18 has been opened upon thecessation of the alternating impulse. The relay 13 holds the heating circuit closed;

When the conversation is terminated and the operator desires to open the heating circuit, a direct currentimpulse is sent over the trunk line 1, 2. This direct currentimpulse energizes relay 14 and opens the contact at 12, the armature of relay 14 being' biased so that the contact at 12 is normally closed. As a result'the heating circuit is opened, the relay 13 becomes deenergized, contact at 11 is broken and the amplifier connections are restored to their original condition.

If desired, additional contacts 19 and 20.

may be provided on relay 16 for the purposeof closingsuitable circuits to transmit the call to a more distant station. For the same reason, additional contacts 21 and 22 may beprovided on the relay 14 to transmit impulses to distant stations for openingthe heating circuits:

In the arrangement shown in Fig. 2 connections-are indicated whereby the heating circuits of the amplifying tubes 23 and 24 of two trunk lines may be controlled and also the heating circuitof amplifier tubes25, which areemployed in phantom circuit, may becontrolled. The trunk lines are indicated at A, B and C, D; andthe phantom line at E, F; The controlof thelieating circuits for the amplifiers employed in the trunk lines A, B and C, D is brought out in the manner described in connection with the arrangement shown in Fig. 1, provisions having been made whereby the operation may The control of the heating circuit for the amplifier tubes 25 in the phantom circuits is as follows:

When an operator at a distant station wishes to put in operation the amplifiers no Q for the phantom circuit, an alternating current impulse is'sent out over the phantom line. This current flows through the condensers 26 to a point 27, and from thence it flows through the primary of transformer 29 to the point 30, thence through condensers 31 and the primary windings of the transformer 5 back to the distant station. The relay 52, which is connected to the sec ondary of transformer .29, is energized and closes the heating circuit of the amplifier tubes 25 in the manner described in connection with Fig. 1.

When the conversation over the phantom circuit has been concluded the operator sends a direct current impulse over the phantom circuit. This impulse flows through the con necting conductors 33 to the mid-point 34: in the vinding of relay 35, thence through the winding of relay 36 to the midpoint of the winding of relay 37, thence through windings of relay 37, and connecting conductors 38 to the conductors of line 0. As a result relay 36 is energized, opening the contact at 39, and thus opening the heating circuit for amplifier tubes 25. Since this direct current flows differentially through the windings of relays 35 and 37, it does not in any way interfere with the operation of the amplifiers in the trunk line circuits.

What I claim as new and desire to secure by Letters Patent of the United States is l. The combination in a thermionic amplifier system of means whereby a circuit for supplying heating current to the cathode of an amplifier from a local source of current may be closed by means of a current impulse of one form supplied from a distant point, and a different means whereby the circuit may be opened by means of a current impulse of a different character from the first which is also supplied from the distant point to a circuit which has different characteristics from that to which the closing impulse is supplied.

2. The combination in a thermionic amplifier system of means whereby a circuit for supplying heating current to the cathode of an amplifier may be closed by means of a current impulse of one form supplied from a distant point, means in addition to the closing means for holding the circuit closed, and means whereby the circuit may be opened by means of a current impulse of a different character from the first which is also supplied from the distant point.

3. The combination in a thermionic amplifier system of means whereby a circuit for supplying heating current to the cathode of an amplifier may be closed by means of an alternating current impulse supplied from a distant point, and means whereby the circuit may be opened by means of a direct current impulse which also supplied from the distant point.

4. The combination in a thern'iionic amplifier system of a relay adapted to effect the closing of a circuit for supplying heating current to the cathode of an amplifier and a second relay adapted to open the heating circuit, circuit means for supplying to one of said relays an alteri'iating current impulse transmitted from a distant point and circuit means for supplying to the other relay a direct current impulse transmitted from the distant point.

5. The combination in a thermionic amplifier system of a relay adapted to effect the closing of a circuit for supplying hcatii'ig current to the cathode of an amplifier and asecond relay adapted to open the heating circuit, circuit means for supplying to one of said relays an alternating current impulse transmitted from a distant point and circuit means for supplying to the other relay a direct current impulse transmitted from the distant point and a third relay for holding the heating circuit closed until the second relay has been operated.

6. The combination in a thermionic amplh fier system of an incoming line, a relay connected in a circuit which is conductirely connected to said line, a second relay connected in a circuit which is inductively connected to said line, a circuit for supplying heating current to the cathode of an amplifier, means whereby said heating circuit may be closed by a. current impulse transmitted over said line to one of said relays, and means whereby said heating circuit may be opened by a current impulse transmitted over said line to the other relay.

In witness whereof, I have hereunto set my hand this 20th day of March,

WALTHER WOLFE. 

